Ecology in Action

Biological diversity should be viewed through the lens of genetic diversity, overall species diversity, and on a broader scale, ecosystem diversity. Small populations have very low genetic diversity, and have high probabilities of extinction. Ecologists use various types of population viability analyses to predict the probability of extinction. Field ecologists collect population data on survival of young and fecundity of females to construct life tables that help with making projections of future population growth. Immigration of individuals from nearby populations can maintain population viability and species diversity. Metapopulations are most viable when they are large and well-connected to numerous subpopulations, so they experience high immigration rates. Humans have caused the decline or extinction of many populations and species by degrading or destroying habitats, by fragmenting habitats, by overexploiting species, and indirectly by introducing non-native (invasive) species to a novel environment. Habitat destruction, habitat fragmentation, and direct exploitation of a naturally small population threaten the viability of the newly discovered Tapanuli orangutans.